Four-strand interleaved-turn transformer winding

ABSTRACT

An interleaved-turn winding for electrical inductive apparatus. Four conduction paths through the windings are provided by interconnections between the coil disks of the winding. Two of the conduction paths begin at an upper coil disk and spiral inwardly toward the center of the winding. These paths are directed to the adjacent and lower coil disk by interconnecting leads and then progress outwardly through the adjacent coil disk. The other two conduction paths begin at the adjacent coil disk and spiral outwardly therethrough and then inwardly through the upper coil disk. High series capacitance is obtained by positioning a conduction path from one pair of conduction paths between the conduction paths of the other pair.

United States Patent 1 Van Nice FOUR-STRAND INTERLEAVED-TURN TRANSFORMER WINDING [75] Inventor: Robert I. Van Nice, Sharon, Pa.

[73] Assignee: Westinghouse Electric Corporation,

Pittsburgh, Pa.

[22] Filed: Sept. 16, 1974 [21] Appl. No.: 506,641

[52] U.S. Cl 336/70; 336/187 [51] Int. Cl. H0lf 15/14 [58] Field of Search 336/69, 70, 186, 187

[56] References Cited FOREIGN PATENTS OR APPLICATIONS 1,147,282 11/1957 France 336/70 Primary Examiner-Thomas J. Kozma Attorney, Agent, or FirmJ. R. Hanway Aug. 12, 1975 [5 7 ABSTRACT An interleaved-tum winding for electrical inductive apparatus. Four conduction paths through the windings are provided by interconnections between the coil disks of the winding. Two of the conduction paths begin at an upper coil disk and spiral inwardly toward the center of the winding. These paths are directed to the adjacent and lower coil disk by interconnecting leads and then progress outwardly through the adjacent coil disk. The other two conduction paths begin at the adjacent coil disk and spiral outwardly therethrough and then inwardly through the upper coil disk. High series capacitance is obtained by positioning a conduction path from one pair of conduction paths between the conduction paths of the other pair.

3 Claims, 2 Drawing Figures 8 6 8 a 4 a s n m m a a Afi 6 A 0 E D A E P A w E QC, fa W E 1 r MI n AMT m\ ll x C m /L w .A C l i I JII 4 C 6 C 2 5 L "2 m FIG.I

FIG. 2

1 FOUR-STRAND INTERLEAVED-TURN TRANSFORMER WINDING BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates, in general, to electrical inductive apparatus and, more specifically, to interleaved windings for power transformers.

2. Description of the Prior Art When the current capacity of a transformer winding is relatively large, it is desirable to use several conductor strands instead of one large conductor. Multiplestrand conductors offer easier handling and lower eddy current losses than large single conductors. As a result thereof, most high-current transformer windings are constructed of multiple-strand conductors.

The use of interleaved winding arrangements to improve the surge or impulse strength of a windingis well known to those skilled in the winding art. However, in general, the winding development and construction requirements become more complicated as the number of strands increases. For this reason, use of interleaved arrangements with multiple-strand windings is somewhat rest rained by the higher cost to construct such windings.

Two and three strand interleaved windings are relatively common and are being used in a variety of applications. Four-strand interleaved windings seem to approach the trade-off point between impulse strength and construction costs. Although a number of fourstrand interleaved winding arrangements are known, there are particular disadvantages associated with each arrangement. A four-strand interleaved winding which offers improved impulse strength over conventional windings is disclosed in British Patent Specification No. 1,099,403. This winding requires the winding of eight strands simultaneously and a large number of lead bends and splices to interconnect the strands in various coil disks.

US. Pat. No. 3,299,385 discloses a four-strand interleaved winding which requires the winding of only four strands simultaneously. However, in some winding applications, it is desirable to have most of the leads, which interconnect the various coil disks, located on the inside of the winding near the winding tube rather than on the outside of the winding. Therefore, it is desirable and it is an object of this invention, to provide a four-strand interleaved winding which is relatively simple to construct and which has most of the interleaving connections located on the inside of the wind- SUMMARY OF THE INVENTION There are disclosed herein new and useful fourstrand interleaved windings which can be constructed by winding with only four conductor spools and which have the connections, which connect together nonadjacent coil disks, located on the inside of the wind- The coil disks of each winding are connected together in such a manner that four conduction paths direct current through each winding. Two conduction paths begin at the outer turn of an upper disk and spiral inwardly through the upper coil disk. These conduction paths are then transferred to the inner turn of an adjacent coil disk where they spiral outwardly through the adjacent coil disk. The conduction paths then proceed to other coil disks in the winding and spiral therethrough in a similar manner.

Two additional conduction paths begin at the inner turn of the adjacent coil disk, or first coil disk from the upper coil disk, and spiral outwardly through the adjacent coil disk. These conduction paths are then transferred to the outer turn of the upper coil disk where they spiral inwardly through the upper coil disk. These conduction paths are then transferred to other coil disks in the winding and spiral therethrough in a similar manner.

A conductor from one of the conduction paths is positioned radially between the conductors which form otherconduction paths to provide the high series capacitance. In one embodiment, one conduction path begins at the outermost conductor location in the upper coil disk. In another embodiment, one conduction path begins at the conductor location which is radially adjacent to the outermost conductor location in the upper coil disk. A

BRIEF DESCRIPTION OF THE DRAWING Further advantages and uses of this invention will become more apparent when considered in view of the following detailed description and drawing, in which:

FIG. 1 is a view of a four-strand interleaved-turn winding constructed according to one embodiment of this invention;

FIG. 2 is a view of a four-strand interleaved-turn winding constructed according to another embodiment of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Throughout the following description, similar reference characters refer to similar elements or members in all of the Figures and drawing.

Referring now to the drawing, and to FIG. 1 in particular, there is shown a four-strand winding 10 of the interleaved-turn type. In this specific embodiment, the winding 10 is positioned around the insulated lowvoltage winding 12 and the magnetic core leg 14. The winding 10 may be represented in various other embodiments without departing from the scope of the invention. For example, the winding 10 could be a lowvoltage winding located adjacent to a magnetic core leg rather than being a high-voltage winding.

The winding 10 consists of the strands or conductors 16, 18, 20 and 22 which form turns within the winding 10. The turn 24 is an outer turn and the turn 26 is an inner turn. The conductors which form the turns 24 the four strand simultaneously on a suitable winding tube, breaking down and rebuilding every other coil disk, and making the proper interconnections and crossovers between the coil disks. Each conductor is individually insulated with conductor insulation to reduce eddy currents, such as the insulation 38 around the conductor 16.

The coil disks 30, 32, 34 and 36 are interconnected by the finish-finish connections 40, 42 and 44, and by the start-start connections 46, 48 and 50. The interleaved pattern provided thereby can be determined by following the conduction paths which progress through the coil disks. The letters A, B, C and D are used to designate the four conduction paths through the winding 10. The numbers associated with the letters at the conductor locations indicate the number of turns the conductor has made around the axis 28 and, therefore, the relative voltage induced therein. This identifying technique permits rapid observation about the theoretical potential difference between various conductor locations.

A first path A begins at location A1 and progresses inwardly to location A2. The identifying nomenclature is established assuming that the coil disks are wound with only two complete four-strand turns. It is emphasized that normally more turns would be included and that the invention is not limited to just two turns. The first path then proceeds across the lead 52 of the startstart connection 46 to the location A3 and then outwardly to the location A4. After the first path proceeds across the lead 54 of the finish-finish connection 42 to the location AS, the pattern of progression of the first path in the coil disks 34 and 36 is similar to that in the coil disks 30 and 32.

A second conduction path C begins at location C1 and progresses inwardly to location C2. The second conduction path then proceeds across the lead 56 of the start-start connection 46 to the location C3 and then outwardly to the location C4. After the second conduction path proceeds across the lead 58 of the finish-finish connection 42 to the location C5, the pattern of progression of the second path in the coil disks 34 and 36 is similar to that in the coil diks 30 and 32.

A third conduction path B begins at location B1 and progresses outwardly to location B2. The third path then proceeds across the lead 60 of the finish-finish connection 40 to the location B3 and then inwardly to the location B4. After the third conduction path proceeds across the lead 62 of the start-start connection 46 to the location B in the coil disk 36, the pattern of progression of the third path in the coil disks 34 and 36 is similar to that in the coil disks 30 and 32.

A fourth conduction path D begins at location D1 and progresses outwardly to location D2. The fourth path then pg ceeds across the lead 64 of the finishfinish connection 40 to the location D3 and then inwardly to the location D4. After the fourth conduction path proceeds across the lead 66 of the start-start connection 46 to the location D5 in the coil disk 36, the pattern of progression of the fourth path in the coil disks 34 and 36 is similar to that in the coil disks 30 and 32.

Another embodiment of the invention is illustrated in FIG. 2. The winding 70 includes the coil disks 72, 74, 76 and 78. The coil disks are disposed around the coil axis 80, the magnetic core leg 82, and the low-voltage winding 84. With the exception of the lead connections to and between the coil disks, the physical construction, and the possible variations thereof, are similar to those mentioned in-describing FIG. 1.

In the winding 70, a first conduction path A begins at location Al and progresses inwardly to location A2. The first path then proceeds across the lead 86 of the start-start connection 88 to the location A3 and then outwardly to the location A4. After the first path proceeds across the lead 90 of the finish-finish connection 92 to the location AS, the pattern of progression of the first path in the coil disks 76 and 78 is similar to that in the coil disks 72 and 74.

A second conduction path C begins at location C1 and progresses inwardly to location C2. The second path then proceeds across the lead 94 of the start-start connection 88 to the location C3 and then outwardly to the location C4. After the second conduction path proceeds across the lead 96 of the finish-finish connection 92 to the location C5, the pattern of progression of the second path in the coil disks 76 and 78 is similar to that in the coil disks 72 and 74.

A third conduction path D begins at the location D1 and progresses outwardly to the location D2. The third conduction path then proceeds across the lead 98 of the finish-finish connection 100 to the location D3 and then inwardly to the location D4. After the third conduction path proceeds across the lead 102 of the finishfinish connection 104 to the location D5 in the coil disk 78, the pattern of progression of the third path in the coil disks 76 and 78 is similar to that in the coil disks 72 and 74.

A fourth conduction path B begins at location B1 and progresses outwardly to location B2. The fourth path then proceeds across the lead 106 of the finish-finish connection 100 to the location B3 and then inwardly to the location B4. After the fourth conduction path proceeds across the lead 108 of the start-start connection 104 to the location B5 in the coil disk 78, the pattern of progression of the fourth path in the coil disks 76 and 78 is similar to that in the coil disks 72 and 74.

The interleaved windings disclosed herein exhibit high series capacitance together with large current carrying capability. The number of strands which must be wound simultaneously is less than that of many prior art arrangements. In addition, interleaving connections between non-adjacent coil disks are made on the inside of the winding where they can be conveniently located on the winding tube underneath the winding, thereby providing a strong and compact winding structure.

Since numerous changes may be made in the above described apparatus, and since different embodiments of the invention may be made without departing from the spirit thereof, it is intended that all of the matter contained in the foregoing description, or shown in the accompanying drawing, shall be interpreted as illustrative rather than limiting.

I claim as my invention:

1. An interleaved winding for electrical inductive apparatus, comprising:

at least first and second coil disks disposed axially adjacent to each other, with each coil disk containing a plurality of conductors spirally disposed around a common axis to form at least inner and outer turns of the conductors;

start-start and finish-finish connections located between the coil disks to provide at least first, second, third and fourth conduction paths through the coil disks, said conduction paths being directed in a first radial direction when progressing towards said axis and in a second radial direction when progressing away from said axis;

said first and second conduction paths beginning at the outer turn of the first coil disk and progressing in the first direction through the first coil disk and which is positioned under the inner turn of the second coil disk, said third coil disk being axially located in the winding with two coil disks between the first and third coil disks.

2. The interleaved winding of claim 1 wherein the first conduction path begins at the outermost conductor location in the first coil disk.

3. The interleaved winding of claim 1 wherein the fourth conduction path begins at the innermost conductor location in the second coil disk. 

1. An interleaved winding for electrical inductive apparatus, comprising: at least first and second coil disks disposed axially adjacent to each other, with each coil disk containing a plurality of conductors spirally disposed around a common axis to form at least inner and outer turns of the conductors; start-start and finish-finish connections located between the coil disks to provide at least first, second, third and fourth conduction paths through the coil disks, said conduction paths being directed in a first radial direction when progressing towards said axis and in a second radial direction when progressing away from said axis; said first and second conduction paths beginning at the outer turn of the first coil disk and progressing in the first direction through the first coil disk and then in the second direction through the second coil disk; said third and fourth conduction paths beginning at the inner turn of the second coil disk and progressing in the second direction through the second coil disk and then in the first direction through the first coil disk; with said third conduction path being radially positioned, in the coil disks, between the first and second conduction paths; said first disk being connected to a third coil disk in the winding by a start-start connection which is positioned under the inner turn of the second coil disk, said third coil disk being axially located in the winding with two coil disks between the first and third coil disks.
 2. The interleaved winding of claim 1 wherein the first conduction path begins at the outermost conductor location in the first coil disk.
 3. The interleaved winding of claim 1 wherein the fourth conduction path begins at the innermost conductor location in the second coil disk. 